Robert Silverberg 
Kingdoms of the Wall [EPUB ebook] 

For Poilar Crookleg, the Pilgrimage to Kosa Saag has been a lifelong dream. Each year twenty men and twenty women attempt to reach the Summit, converse with the gods, and return with new knowledge. A few Pilgrims return as madmen. Most are never seen again.Poilar and his childhood friend Traiben are determined to survive the terrifying journey not as madmen but as teachers of wisdom. Traversing mysterious Kingdoms and blasted landscapes, braving ghosts and monstrous apparitions, they will arrive at the secret of the gods themselves — a secret that will shatter centuries of belief and change their world forever.